DESCRIPTION: The proposed research will investigate the modification of Dental unit water lines with a novel yet inexpensive photosensitizer for singlet oxygen. The dissolved oxygen in the water is promoted to singlet oxygen using low power visible light. The light that normally passes into the translucent tubing from room light should be sufficient. Singlet oxygen has long been known as a potent disinfectant. This Phase I research will verify that polyurethane ester tubing, that which is most commonly used for Dental unit water lines, may be chemically modified with the photosensitizer. A second form of tubing, based on PVC, also will be produced using the same chemistry to increase the probability of a useful product. The effects of the chemical process and singlet oxygen on the tubing material and the effects of the plasticizers used in the tubing on the photosensitizer will be examined. The lighting requirements for the photosensitizer will be investigated both cross-sectionally and laterally. Since such a small amount of light is required, the translucent tubing may be used to distribute the light into shaded regions of the Dental unit. At each stage, tubing will be subjected to contaminated water and evaluated for the development of biofilm.